In the early 20th century, a new type of semiconductor junction was produced. The semiconductor junction herein referred to is a diode that is capable of producing light; this type of diode is now commonly known as a Light Emitting Diode (LED). LEDs have been in commercial use for several decades. Initially they were used as indicators in electronic devices such as in television sets, radios, telephones, etc. Essentially in the beginning, commercially available LEDs had weak luminous flux compared to conventional light sources, and their luminous flux was insufficient to provide adequate lighting for illuminating an area, which incandescent lighting was excellent at providing.
The development of LEDs has continued and progressed, and researchers have progressively come up with LEDs with greater luminous flux. In fact, they could now be used in all kinds of lighting applications whereas in the past only conventional light sources were applicable. As a result, they are slowly but surely replacing conventional light sources such as found in flashlights, car lights, traffic signalization, etc.
The principal advantages of the LED over many other types of lighting are: its low energy consumption, and its long life span, which in general extends to fifty thousand hours or more. Although LEDs have been improved to provide greater luminous flux, their use for general lighting is not that extensively accepted by manufacturers and consumers. One of the reasons for its low level of acceptance, as opposed to incandescent lighting, is its lower capacity to provide an acceptable level of color rendering. Color rendering refers to a quantitative measure of the ability of a light source to reproduce colors of various objects faithfully in comparison with an “ideal” source of lighting. Color rendering capability is measured through use of a color rendering index, established by the International Commission on Illumination (CIE).
Incandescent light, for a color temperature range of under 5000K, provides a color rendering index that is optimal. Other sources of light are used as references, for color temperatures of above 5000K. More specifically, on a scale from zero to a hundred, incandescent light has a color rendering index that is equal to one hundred for color temperatures below 5000K. In comparison, white light that is produced by LEDs, typically combine LEDS of various colors including at least combinations of Red Green Blue (RGB). As LEDs' specifications vary from one manufacturer to another, and those specifications vary with the temperature of operation of the LEDs and forward current, it becomes very difficult for lighting manufacturers to integrate LEDs in their domestic applications, as the resulting white light does not render a color rendering index comparable to incandescent light. Thus, notwithstanding the economic and energy savings advantages of LEDs over conventional light sources, lighting manufacturers and domestic consumers do not rely on this technology.
It would therefore be useful to have a tool, method, system and light source that are adapted to optimize use of combination of LEDs for producing white light. It would be a further advantage to identify an optimized combination of LEDs having high color rendering index for “white light” applications.